Waves Unit C- Chapter 1.2 Waves Have Measurable Properties Answer Key Name: Date: Core: Directions: Read pages C16-C21 and answer the following questions. 1. What are the 3 properties of a wave that can be measured? Answer: Amplitude, Wavelength, Frequency 2. What is the crest? Answer: The highest point, or peak, of a wave. 3. What is the trough? Answer: The lowest point, or valley, of a wave. 4. What is amplitude? Answer: Amplitude is the distance between a line through the middle of a wave and a crest or a trough. 5. What does amplitude measure in an ocean wave? Answer: The amplitude of an ocean wave is measured as the wave rises above, or dips below the original position, or rest position. 6. Amplitude is an important measurement, because it indicates how much ___energy___________ a wave is carrying. 7. What is wavelength? Answer: Wavelength is the distance from one crest or trough to the next. 8. What is frequency? Answer: The number of wavelengths passing a fixed point in a certain amount of time is called the frequency. 9. What does the word“frequent” mean? Answer: The word frequent means “often”. 10. How is frequency measured? Answer: Frequency is measured by counting the number of crests and troughs that pass by a fixed point in one period. 11. How is amplitude related to energy? Answer: The larger the amplitude the more energy a wave carries. 12. How many wavelengths are shown in this diagram? How do you know? Answer: The diagram shows 2 wavelengths. Because it is shown from trough to trough. 13. Draw the “Wave Properties” diagram at the bottom of page C17? Answer: Diagram on page C17. 14. Are frequency and wavelength related? Answer: Yes 15. How are frequency and wavelength related? Answer: The larger the amplitude, the more energy a wave carries. 16. Answer the following questions from the “Spring Toy” Visual on Page C18. A. What repeating pattern do you observe? Answer: Bunching up/spreading Out B. What part of the spring coil corresponds to the wave crest? Answer: Where the coils are spread out. C. What part of the spring coil corresponds to the wavelength? Answer: Where the coils are bunched up. 17. How are longitudinal waves measured? Answer: Amplitude is a measure of how compressed the medium gets. Wavelength is a measure of the distance between compressions. Frequency is the number of compressions that occur within a certain time. 18. Answer the following question from the “Graphing A Wave” Visual on page C19. A. What are the different parts of the visual on this page? Answer: The photograph, 3 Diagrams, and a Graph. B. What does the curved line on the graph represent? Answer: The wave in the photograph. C. What do the x-axis and y-axis represent? Answer: Time in seconds, and distance (amplitude) in meters. D. What do the bubble pictures above the graph show? Why are they important? Answer: The buoy bobs up and down as a wave passes underneath, it is the fixed point from which frequency and other wave measurements can be taken. 19. How many seconds does it take for one wavelength to pass? Answer: 4 Seconds 20. How much of the wave passes in one second? Answer: One-fourth of the wave. 21. How can wave speed be measured? Answer: Speed= Wavelength X Frequency 22. Do different types of waves travel at different speeds? Answer: Yes! 23. Calculating Wave Speed. A. Look at the sample problem on page C21. B. Do the “Practice the Math” (Activity 1 & 2) Answers: 1. 20 mls 2. 1 cmls 24. How do geologists use sound waves to find oil in the ground? Answer: The geologists use the wave speed equation to find oil deep underground. They send sound waves into the ground. The speed of the waves that bounce back indicates what the ground is made up of. This is possible because sound travels at different speeds through different kinds of rock. The geologists then use this information to drill for oil and how far down they will need to go. Chapter 1.2- Review- Page C21 Directions: Complete questions 1-5 on C21. Only write your answers. Answers: 1. See Page C17. 2. Wavelength & Frequency 3. Look at a fixed point below, and time how many waves pass that point within a unit of time. 4. 0.5 m 5. You should record the amplitude, wavelength, and frequency of waves at different times during the day. Changes in these measures could help indicate the approach of a storm.